Iranian Foreign Minister Abbas Araghchi has vowed support for Tehran's "friends" in Lebanon while on his first visit to Beirut since fighting between Israel and Hezbollah militants intensified last month.

"Be sure that the Islamic Republic of Iran is and will be firmly standing by the friends in Lebanon," Mr Araghchi told reporters, adding that Tehran supported Lebanon, its Shiite Muslim community and Hezbollah, "and it was necessary to say this in person".

Iran's most senior diplomat also said his presence in Beirut "in these difficult circumstances" was the best evidence that Iran stood by Lebanon and supported the Shiites.

He also backed efforts for a ceasefire in Lebanon, on the conditions that Hezbollah also backed the ceasefire and it was agreed simultaneously with a ceasefire in Gaza.

"We support efforts for a ceasefire on the condition that it would be acceptable to the Lebanese people, acceptable to the resistance, and thirdly, it would be synchronised with a ceasefire in Gaza," he said.

The deputy commander of Iran's Islamic Revolutionary Guards Corps, the country's most powerful military force, said meanwhile that Iran would strike Israeli energy and gas installations if Israel attacked it.

"If the occupiers make such a mistake, we will target all their energy sources, installations and all refineries and gas fields," Iranian news agency SNN quoted Ali Fadavi as saying.

His comments came after Iran's Supreme Leader Ali Khamenei delivered a rare public sermon in which he railed against Israel and the US.

Israel and Hezbollah have traded fire across Lebanon's southern border almost daily since the day after Hamas's cross-border terror attack on October 7, 2023, in which the militants killed 1,200 people and took 250 others hostage.

More than 41,000 Palestinians have since been killed in the territory, and just over half the dead have been women and children, according to local health officials.

Nearly 2,000 people have been killed in Lebanon in that time, most of them since September 23, according to the Lebanese Health Ministry.

Israel pounds Beirut with consecutive air strikes

A new wave of air strikes in Beirut came after Israel warned people to evacuate communities in southern Lebanon that were outside a United Nations-declared buffer zone, as the year-long conflict between Israel and the Lebanese terrorist group Hezbollah continued.

Lebanon's state-run National News Agency reported there were more than 10 consecutive air strikes in the area late on Thursday.

Israel launched a ground incursion into Lebanon on Tuesday and its forces have been clashing with Hezbollah militants in a narrow strip along the border.

A series of attacks before the incursion killed some of the group's key members, including longtime leader Hassan Nasrallah.

The blasts overnight rocked Beirut's southern suburbs, sending huge plumes of smoke and flames into the night sky and shaking buildings kilometres away in the Lebanese capital.

Lieutenant Colonel Nadav Shoshani said the military was still assessing the damage caused by air strikes in southern Beirut on Thursday night, which he said targeted Hezbollah's intelligence headquarters.

On Friday, the Israel Defense Forces (IDF) said it had killed 250 Hezbollah fighters during the past four days after launching its ground incursion in southern Lebanon. 

In a statement, the military said "250 Hezbollah terrorists were eliminated, of which 21 were commanders during four days of precise operation in southern Lebanon".

"Over 2,000 military targets have been struck."

In a separate statement, the IDF said two of its soldiers from the Golani Brigade had been killed in combat in northern Israel.

It said two others had been severely injured.

Masnaa Border Crossing cut off

The National News Agency also reported that an Israeli air strike led to the closure of the road near the busy Masnaa Border Crossing, from which tens of thousands of people fleeing war in Lebanon had crossed into Syria over the past two weeks.

It gave no other details.

Dama Post, a pro-government Syrian media outlet, said Israeli warplanes fired two missiles — damaging the road between Masnaa Border Crossing in Lebanon and the Syrian crossing point of Jdeidet Yabous.

The air strike that cut off the busiest border crossing between the two countries came a day after an Israeli military spokesperson said Hezbollah had been trying to transport military equipment through the border crossing.

Hezbollah is believed to have received much of its weaponry from Iran via Syria. The group has a presence on both sides of the border, a region where it has been fighting alongside Syrian President Bashar al-Assad's forces.

The strike marked the first time this major border crossing had been cut off since the beginning of the war.

Lebanese General Security recorded 256,614 Syrian citizens and 82,264 Lebanese citizens crossing into Syrian territory between September 23 — when Israel launched a heavy bombardment of southern and eastern Lebanon — and September 30.

There are half a dozen border crossings between the two countries and most of them remain open. Lebanon's minister of public works said all border crossings between Lebanon and Syria work under the supervision of the state.

Meanwhile, the Israeli army said it carried out a strike on Thursday in Tulkarem, a militant stronghold in the West Bank, in coordination with the Shin Bet internal security service.

The Palestinian Health Ministry said 18 people were killed in an Israeli strike on a refugee camp there.

Israeli military strikes across the Gaza Strip killed at least 29 Palestinians on Friday, medics said, and sirens blared in southern Israel in response to renewed rocket fire from militants in the Palestinian enclave.

The new rocket fire indicated that Hamas was still able to fire projectiles into Israel even after a year-long Israeli aerial and ground offensive in Gaza.

On Friday, the Israeli military said sirens sounded in southern Israel for the first time in around two months.

"Almost a year after October 7, Hamas is still threatening our civilians with their terrorism and we will continue operating against them," it added.

Violence has flared across the Israeli-occupied territory since the Israel-Hamas war erupted in October 2023. Tulkarem and other northern cities have seen some of the worst violence.

Evacuation flights confirmed for Australians

Qantas has confirmed it will run two flights from Cyprus to Sydney to bring home Australians leaving the conflict in Lebanon, Australian Foreign Minister Penny Wong said.

Senator Wong released a statement confirming the flights would be free of charge, with vulnerable passengers prioritised.

Two government-supported charter flights carrying up to 500 passengers will depart the Lebanese capital of Beirut for Cyprus on Saturday.

Senator Wong said further flights were planned for subsequent days and would be subject to demand.

"The Department of Foreign Affairs and Trade will be in contact with registered Australians to facilitate their departure and will continue to provide updates to registered Australians," the minister's statement said.

A spokesperson for Assistant Foreign Minister Tim Watts said 2,338 Australians and their immediate family members had registered to depart Lebanon.

Supreme Leader Khamenei says Muslim nations share 'common enemy'

Iran's Supreme Leader Ali Khamenei has delivered a public sermon for the first time in almost five years.

He had a rifle by his side as he addressed thousands of worshippers carrying portraits of slain leaders of Iran's "Axis of Resistance" against Israel and the United States.

During the sermon, he said Muslim nations had a "common enemy" and had to "strap the belt of defence from Afghanistan to Yemen, from Iran to Gaza and Lebanon".

He argued Hamas's October 7 attack on Israel was "logical and legal" and "the brilliant action a couple of nights ago by our armed forces" during Iran's missile attack on Israel was "legal and legitimate".

The missile attack was the "minimum punishment" for Israel's crimes, he said.

"Every country has the right to defend itself from aggressors," he said.

"Israel is pretending to win through assassinations and civilian killings.

"What is accumulated from Israel's recent behaviour is increasing anger and strengthening resistance motives."

He went on to say Iran would "not procrastinate or rush to carry out its duty" and that Israel would never be victorious over Hamas or Hezbollah.

He also accused the US of preserving Israel's security as a cover for seizing the region's resources, with an aim to make Israel "a gate to energy exporting from the region to Europe".

ABC/wires